Knife sharpening machines have been the subjects of a great many patents. A patent to Burns, U.S. Pat. No. 2,228,385 discloses a pair of motor driven sharpening stone assemblies, each made up of a plurality of spaced circular sharpening stones mounted on arms that can be moved around a pivot point coincident with the axis of a motor shaft, to vary the angle of intersection of the overlapped peripheries of the grinding elements. The machine of Burns is belt driven. Lindhal U.S. Pat. No. 2,617,235 shows a hand cranked sharpening device, in which a gear, driven by the crank, engages pivot gears mounted on arms that are biased continuously by a spring toward one another, so that sharpening disks carried by the arms are always in engagement, even when they wear. In such an arrangement, a knife being sharpened tends to move the sharpening disks away from one another, so that, depending upon the amount of pressure applied to the knife, the angle of the cutting edge and the amount of abrasion will vary. Nichols, U.S. Pat. No. 2,482,633 discloses a motor driven sharpening unit, with a pulley from a motor to a sheave to drive one of two idler gears, the other of which is mounted on a pivot point of a yoke which can be moved about that pivot point by a knurled knob, to move grinding wheels on a shaft carried by the yoke toward and away from grinding wheels carried on a shaft fixed against translation. Two of the grinding wheels meet face to face, so that the amount of the adjustment permitted is limited to compensation for wear of the abutting grinding wheels. A patent to Allan, U.S. Pat. No. 3,484,997 discloses a motor driven knife sharpener, in which a gear on the motor shaft drives mediately a gear mounted on a pivot axis of an arm which carries at its upper end a gear mounted on a shaft driving abrasive disks mounted on the shaft, so as to maintain a desired overlap of the abrasive disk as the diameter of the disks is reduced by wear. Friel U.S. Pat. No. 4,807,399 discloses a machine with a pre-sharpening section and two honing sections. Both the honing stones and the sharpening stones are driven by a single motor. A sharpening machine sold under the trademark PrimEdge, by Cozzini Inc., also has honing and sharpening wheels driven by a single motor, through belts.
Among the objects of this invention are to provide a commercial or industrial knife sharpener that is sturdy, economical to manufacturer, dependable, easily maintained, and readily adjustable to produce different edge angles.
Other objects will become apparent to those skilled in the art in light of the following description and drawings.